The present invention relates to a retaining arrangement for restricting an axial movement of a rod member supported by a stay member by attaching a retaining assembly onto an outer circumferential surface of the rod member adjacent to the stay member, and in particular to a retaining arrangement for a rod member suitable for use in connection with a stabilizer for a vehicle suspension system.
In case of a stabilizer for vehicles such as an anti-roll bar which is curved at both ends into the shape of letter-U, for instance, each end of the middle section of the rod member (stabilizer) adjacent to the two curved portions thereof are supported by the vehicle body, and the outer ends of the curved portions are supported by the corresponding suspension arms. The support arrangement by the vehicle body typically involves the use of a rubber bush surrounding the stabilizer and a U-shaped stay wrapped around the rubber bush and attached to the vehicle body.
However, the stabilizer may be subjected to a lateral force or an axial force at the middle section of the stabilizer during the operation of the vehicle, and such a lateral force could be so great that the rubber bush and the stay are incapable of properly withstanding it. When the deformation of the rubber bush is excessive, adjacent components may rub each other, and this could cause undesired noises, and damages to the link member that is attached to the outer end of each curved portion. In particular, such occurrences tend to impair the durability and the reliability of the stabilizer, and the ride quality.
In view of this fact, it has been proposed to securely fit and crimp a metallic washer onto a part of the stabilizer adjacent to the corresponding rubber bush so as to restrict the axial deformation of the rubber bush. However, this proposal requires the metallic washer to be fitted from an end of the stabilizer, and this impairs the efficiency of the production process, and could reduce the resistance of the stabilizer against corrosion because the crimped portion may not be properly coated by paint.
It has also been proposed to fit another rubber bush having flanges on either axial ends thereof onto the part of the stabilizer adjacent to the existing rubber bush, in place of the washer, and secure this new rubber bush with a clip band so as to control the axial deformation of the existing rubber bush. However, the assembling of the new rubber bush and the clip band has to be carried out manually, and it results in a significant reduction in the production efficiency. Furthermore, the necessary mechanical resistance of at least 2 kN against the lateral deformation may not be ensured because the new rubber bush tends to relatively readily deform, and may not be entirely adequate as a retaining assembly.
Further, Japanese UM laid open publication No. 04-133907 discloses the use of two semi-annular halves which can be combined into a fully annular member fitted around the stabilizer. The stabilizer is provided with an annular groove for partly receiving the fully annular member, and the annular member is then covered by a rubber bush.
This arrangement prevents the lateral shifting of the rubber bush, but the annular groove formed around the stabilizer not only causes a stress concentration and reduces the torsional mechanical strength of the stabilizer, but also may impair the performance of the torsion bar. It could be compensated by increasing the outer diameter of the stabilizer, but the resulting increase in size and weight is not desirable.
The same problem exists not only in stabilizers but also in any other supporting structures for a rod member where the axial shifting of the rod member is desired to be prevented.
The present invention was made in view of such problems of the prior art, and its primary object is to provide a retaining arrangement for a rod member which can prevent the lateral shifting of the rod member by using a simple structure, and which is suited for an automated assembly process while ensuring a sufficient durability and mechanical strength.
According to the present invention, such an object can be accomplished by providing a retaining arrangement for restricting an axial movement of a rod member supported by a stay member, comprising: a tubular retaining assembly fitted on the rod member adjacent to the stay member; and a rugged member interposed between an outer circumferential surface of the rod member and an inner circumferential surface of the retaining assembly, and pushed into the material of at least one of the retaining assembly and the rod member.
The rugged member may comprises either abrasive grains interposed between the outer circumferential surface of the rod member and the inner circumferential surface of the retaining assembly or a rugged surface pattern formed at least in one the of the outer circumferential surface of the rod member and the inner circumferential surface of the retaining assembly. In the former case, the abrasive grains may be mixed with a bonding agent which is coated on a corresponding surface so as to simplify the assembling process. In either case, the retaining assembly can be sufficiently firmly attached to the rod member without requiring any bulky, complex or expensive arrangement and without diminishing the mechanical strength and performance of the rod member.
In particular, when the rod member consists of an automotive stabilizer, it is preferable to be able to fit the retaining assembly onto the rod member from sideways. To achieve this goal, the retaining assembly comprises either a plurality of part-annular segments which are mutually connected to one another via an engagement arrangement so as to jointly form an annular shape closely surrounding the rod member or a single C-shaped member having an relatively flexible middle part, and an engagement arrangement formed on opposing ends thereof so as to form an annular shape closely surrounding the rod member when the opposing ends are joined to each other. The engagement arrangement preferably comprises a recess and a projection having an enlarged head which are formed at the opposing ends of the C-shaped member, respectively, the projection being adapted to be crimped or press fitted into the recess.
When it is desired to reduce the pressure that is required to fully engage the engage arrangement while pressing the remaining part of the retaining assembly onto the rod member, the retaining assembly may have a shape selected from a group consisting of ellipsis, trapezoid and polygon when the part-annular segments are combined without placing the engagement arrangement fully engaged with each other, the shape conforming to the outer circumferential surface of the rod member when the engagement arrangement is fully engaged.
Preferably, the retaining assembly essentially consists of aluminum or an aluminum alloy for the convenience of handling. The abrasive grains may consist of readily available abrasive grains such as synthetic alumina abrasive material and synthetic silicon carbide abrasive material.